Okay, I've reviewed the online man page for date and time functions, and I've played with
several likely candidates, and I am still having trouble subtracting two arbitrary
Datetimes to get something that is useful. A simple subtraction yields the least useful
thing possible: a modulo-100 difference of modulo-60 quantities. Other functions yield the
proper answer, but not for a quantity of time that rolls over midnight, etc.
Surely, there are tons of payroll apps that subtract the punch-out from the punch-in to
come up with a quantity of time?
What is YOUR favourite way of coming up with a quantity of time as the difference between
two arbitrary Datetimes? Did I overlook something simple? Do I need to convert the two to
scalar integers first?